A life course epidemiology approach to climate extremes and human health
Authors: Kate Burrows, Elizabeth Fussell
Journal: The Lancet Planetary Health (2022)

Future generations of people worldwide will experience more frequent climate extremes, including extreme temperature, precipitation, and weather events, than current and past generations. A child born anywhere in the world in 2020 is predicted to experience 4–7 times more heatwaves during their lifetime compared with a child born in 1960.1Thiery W Lange S Rogelj J et al.Intergenerational inequities in exposure to climate extremes.Science. 2021; 374: 158-160Crossref PubMed Scopus (98) Google Scholar Extreme heat is associated with acute health effects, including excess mortality and morbidity associated with renal and respiratory diseases.2Kovats RS Hajat S Heat stress and public health: a critical review.Annu Rev Public Health. 2008; 29: 41-55Crossref PubMed Scopus (1175) Google Scholar Different climate-related events are associated with various health outcomes, including injury and infectious diseases associated with flooding or increased risk of vector-borne illnesses associated with changes in precipitation.3McMichael AJ Woodruff RE Hales S Climate change and human health: present and future risks.Lancet. 2006; 367: 859-869Summary Full Text Full Text PDF PubMed Scopus (1763) Google Scholar To investigate how extreme climate exposures will affect human health in present and future generations of people, we propose a life course epidemiology approach to assess the relationship between climate extremes and human health (LCE-CEHH). This Comment focuses attention on the research questions and data that are necessary to answer important questions about the effects of exposure to climate extremes at each life course stage, the cumulative effect of climate exposures over a life course, and changes in the effects of exposures across birth cohorts as climate change-related exposures become more frequent and intense than in the past. The life course approach was pioneered by social scientists who investigated the effects of deleterious early life experiences on outcomes in later life and the differences in the prevalence and types of these effects across population subgroups.4Elder GH Johnson MK Crosnoe R The emergence and development of life course theory.in: Mortimer JT Shanahan MJ Handbook of the life course. Springer, Boston, MA2003: 3-19Crossref Google Scholar Health scientists extended this approach to life course epidemiology (LCE) to study the relationship between early psychosocial, behavioural, and environmental exposures and health in later life.5Kuh D Shlomo YB A life course approach to chronic disease epidemiology. Oxford University Press, Oxford1997Google Scholar An important finding of LCE is that the health effects of early-life exposures can be acute and remain latent for years or decades.6Almond D Currie J Killing me softly: the fetal origins hypothesis.J Econ Perspect. 2011; 25: 153-172Crossref PubMed Scopus (730) Google Scholar Most literature on climate change-related exposures and health focuses on acute or short-term effects.7Zhang Y Yu C Wang L Temperature exposure during pregnancy and birth outcomes: an updated systematic review of epidemiological evidence.Environl Pollut. 2017; 225: 700-712Crossref PubMed Scopus (132) Google Scholar, 8De Rubeis V Lee J Anwer MS et al.Impact of disasters, including pandemics, on cardiometabolic outcomes across the life-course: a systematic review.BMJ Open. 2021; 11e047152Crossref PubMed Scopus (22) Google Scholar Incorporating an LCE approach into climate and health research would expand this literature to understand the latent effects of early-life exposures over the entire life course. An LCE-CEHH approach will focus attention on the acute health effects of climate change-related exposures that occur at all ages, as well as the delayed effects of single or cumulative climate exposures. Importantly, an LCE-CEHH approach will compare health effects across birth cohorts to investigate the effect of increasingly frequent and intense climate change-related exposures on human health, as well as the protective effects of possible adaptations made by individuals or societies. The figure represents the intersection of cumulative environmental exposures, age, and birth cohorts to illustrate the data coverage that is needed to support LCE-CEHH research. The figure shows how exposures to climate extremes and weather-related disasters accumulate with age and increase across birth cohorts, with the simplifying assumption that the number of extreme climate events increases by one per decade. Identifying or creating health datasets that follow this structure would allow researchers to investigate novel hypotheses related to climate and health, such as identifying pathways from a climate change-related exposure to a specific health outcome in later life3McMichael AJ Woodruff RE Hales S Climate change and human health: present and future risks.Lancet. 2006; 367: 859-869Summary Full Text Full Text PDF PubMed Scopus (1763) Google Scholar or establishing the effectiveness of adaptations to health-care systems in protecting health.9Ebi KL Vanos J Baldwin JW et al.Extreme weather and climate change: population health and health system implications.Annu Rev Public Health. 2021; 42: 293-315Crossref PubMed Scopus (148) Google Scholar Each element of the figure relates to a broad hypothesis in LCE-CEHH research. For the first element (environmental exposures), we hypothesise that each additional climate change-related exposure will increase the likelihood of poor health outcomes for individuals in later life, as well as the likelihood of morbidity and mortality overall. The second element (age) complicates the previous hypothesis by positing that the effects of environmental exposures depend on age; infants, children, and older adults are typically more susceptible to adverse health outcomes related to climate extremes. The third element (birth cohort) proposes that cohorts born in the past few decades will experience more environmental exposures than earlier cohorts. We assume that younger generations will have worse health effects than older generations due to increased accumulated climate change-related exposures. If not, individual and societal adaptations to climate change might be protective. A practical approach to implementing LCE-CEHH research is to combine spatially explicit longitudinal population data, health data, and climate change-related data using data linkage methods. High-resolution spatial and temporal climate data already exist, and continue to improve. However, the small amount of population health data with long-term follow-up remains an important obstacle for LCE-CEHH research. Large administrative datasets, such as electronic medical records from public and private insurers or datasets linking census data with cause of death and other health and demographic records, provide comprehensive population information that can be matched to high-resolution environmental and geospatial information.10Xie S Greenblatt R Levy MZ Himes BE Enhancing electronic health record data with geospatial information.AMIA Jt Summits Transl Sci Proc. 2017; 2017: 123-132PubMed Google Scholar Data linkage provides an exciting opportunity, but is limited by the availability of datasets with personally identifiable information that allow for linkage at the individual level, as well as the availability of important measures, such as medical diagnoses, medical treatments, health behaviours, socioeconomic status, and demographic characteristics. Datasets with personally identifiable information are becoming more readily available but require secure computing infrastructure to prevent misuse of data and protect privacy. An LCE-CEHH approach can inform interdisciplinary collaborations between social scientists, epidemiologists, and climate scientists, resulting in the construction of novel longitudinal datasets that can be used to answer important research questions about the health effects of climate change. This information is essential to prepare for and respond to the effects of future climate extremes and weather-related disasters. KB was supported by a Voss Postdoctoral Research Fellowship and by a Dan David Prize Scholarship Award. BF received funding through the Eunice Kennedy Shriver National Institute of Child Health and Human Development (P2C HD041020, R01 HD093002).